A camera calibration apparatus is known as an apparatus for calibrating a camera based on the plane projective transformation for performing a calibrating operation which includes arranging planar calibration indexes having the coordinate information on at least four points in a first plane, inputting a captured-image surface of the camera including the calibration indexes as a second plane, specifying points that are present in the second plane and correspond to predetermined portions of the calibration indexes, and calculating a homography between the first plane and the second plane based on the corresponding relationships among at least four points shareably included in both the first plane and the second plane (see Patent Document 1, for example). In this apparatus, the calibration indexes are arranged in a photographing region to obtain, based on the photographed calibration indexes, the homography which is a transformation matrix representing the corresponding relationship between the coordinates of a captured image (captured-image system coordinate positions) and the coordinates of a transformed image (plane coordinate system coordinate positions). Such camera calibration is advantageous in that no adverse influence is exerted from a setting error of the camera because the corresponding coordinates are designated between the captured image and the transformed image without requiring camera external parameters or camera internal parameters and based on the calibration indexes that are actually photographed owing to the principal of the plane projective transformation.